Neonatal and pediatric intensive care still involves performing painful needle punctures to obtain blood samples for routine clinical monitoring. Pain management in the neonatal setting is often achieved by long term, continuous intravenous infusion of morphine or related compounds. It has become increasingly clear; however that long term use of opioid compounds in neonates is likely to have significant deleterious neurological effects. Unfortunately, the very nature of neonates (lower weight and incomplete and varied metabolic development) complicates pharmacokinetic studies and modeling. New analytical platforms are needed to enable studies of commonly used compounds in this patient population. Non- or minimally-invasive microfluidic platforms with the ability to address multiple analytes in flexible manner have great promise in improving neonatal pain management and patient outcomes. This project will apply a relatively new mode of detection, backscattering interferometry (BSI) in conjunction with novel DNA aptamers (binding agents) to detect and quantify important opioids used for pain management in neonates as well as propofol, an important agent used for general anesthesia. We will also generate the necessary aptamers for detection of the urinary metabolites of these compounds. The developed platform only requires 1 microliter or less of urine and will enable studies and possibly personalized dosing of therapeutic compounds in neonates. Because of our expertise to rapidly develop aptamers to small molecules, in Phase II we will be in an excellent position to expand the menu of assays and translate them to the clinic with a recently-developed benchtop BSI instrument.